Longitudinal Survey of Pathogenic Leptospira Species at a Major Park in Sydney, Australia.

Since leptospirosis' re-emergence in Sydney, Australia, concerns about the risk of exposure to pathogenic Leptospira species at urban parks have risen. The current longitudinal environmental survey investigated the temporal detection of pathogenic Leptospira at a major recreational park and explored whether the presence of a flying-fox (Pteropus spp.) camp affects soil Leptospira detection. From February to October 2024, environmental samples and voided faecal samples (flying-fox faeces, and goose faeces as controls) were collected from Centennial Park, Sydney. The samples were tested by a diagnostic 16S rRNA TaqMan quantitative PCR (qPCR) assay, and time series of the monthly minimum cycle threshold (Ct) values were generated to assess cross-correlation. Over the nine-month study period, pathogenic Leptospira was consistently detected in soil and water samples. Despite not being a known reservoir of Leptospira, three voided goose faecal samples tested qPCR-positive (Ct 38.22-38.84). There was no difference in qPCR results of soil collected from the flying-fox camp and another nearby location. The water Ct time series was not correlated with monthly precipitation, but was positively cross-correlated with the Ct time series of soil collected at the flying-fox camp one month prior. Overall, the results suggested temporal ubiquity of pathogenic Leptospira at this park. No direct evidence of flying-foxes' contribution to the environmental Leptospira burden at the park was uncovered, but mechanical movement of Leptospira between soil and water, and the role of birds as mechanical vectors, need further research.